1.Potentiometric determination of the standard potential of the As(V)/As(III) couple.

Pesavento M1. Talanta. 1989 Oct;36(10):1059-64.

The potential of the As(V)/As(III) half-cell was measured at 25 degrees with a glass electrode as reference electrode in order to eliminate the liquid-junction potential. Rapid and reproducible values could be obtained only in the presence of iodide, which increases the rate of electron-exchange between the two oxidation states of arsenic, but only at hydrogen-ion concentrations higher than about 0.5M. Extrapolation to zero ionic strength was therefore required to obtain the standard potential. A value of 573 +/- 2 mV was calculated for the half-reaction AsO(OH)(3) + 2e(-) + 2H(+) right harpoon over left harpoon As(OH)(3) + H(2)O.

Our aim was to evaluate if loading prepubertal ovine oocyte with trehalose would impact on their further developmental potential in vitro and if it would improve their survival to vitrification procedures. COCs matured in vitro with (TRH) or without (CTR) 100mM trehalose were tested for developmental potential after in vitro fertilization and culture. Trehalose uptake was measured by the antrone spectrophotometric assay. No differences were recorded between the two experimental groups in fertilization rates (91.1 CTR vs 92.5% TRH), cleavage rates calculated on fertilized oocytes (96.1 CTR vs 95.4% TRH), first cleavage kinetic (56.1 CTR vs 51% TRH), and blastocyst rates (14.3 CTR vs 13.0% TRH). Anthrone assay revealed that in TRH group trehalose concentration/oocyte was 2.6microM. MII oocytes were then vitrified using cryoloops in TCM 199 containing 20% FCS, sucrose 0.5M, 16.5% Me(2)SO, 16.5% EG and plunged in LN(2). After warming, oocytes from TRH and CTR groups were tested for membrane integrity using the propidium iodide (PI)/Hoechst differential staining, and for developmental ability after in vitro fertilization.

The methyl isobutyl ketone extraction of 15 elements (Cu, Ag, Zn, Cd, In, Tl, Ge, Sn, As, Sb, Bi, Se, Te, Mo and Pd) as iodide complexes from 0.1-5 M sulphuric acid/0.01-0.5M potassium iodide media has been studied. At the optimum potassium iodide concentrations, and a 1:2 v v ratio of organic to aqueous phase, Cu(II), Ag, Cd, In(III), Tl(III), Sb(III), Bi, Te(IV) and palladium(II) are completely extracted in a single step from 1-5M sulphuric acid. All these elements except palladium are also quantitatively extracted from 0.05-0.5M iodide/2M sulphuric acid. Zn, Sn(IV) and As(III) are completely extracted at high acid and iodide concentrations, and at the highest concentrations of acid and iodide investigated, Ge is partly extracted and Mo(VI) is slightly extracted. The extraction of Se(IV) is incomplete because of its reduction to the elemental state by iodide. The back-extraction of the elements has also been investigated and the forms in which they are extracted and potential analytical separations and interferences are discussed.

4.Addition of ficoll and disaccharides to vitrification solutions improve in vitro viability of vitrified equine embryo.

The aim of the present study was to evaluate the in vitro viability of equine embryos vitrified in three different solutions. Day 6 and 6.5 embryos were measured and morphologically evaluated. Only grade 1 or 2 morulae and early blastocysts were vitrified. Eighteen embryos were distributed in Group 1: 40 percent ethylene glycol in PBS, Group: 2 and 3: 40 percent ethylene glycol, 18 percent Ficoll, 0.3M sucrose or 0.3M trehalose in PBS, respectively. The vitrified embryos were loaded individually into 0.25 ml straws, which were cooled and immersed in liquid nitrogen. After warming at 20 degree C for 20s, the embryos were expelled out into 0.5M sucrose in PBS and transferred to PBS solution. The embryonic diameter was measured again and morphology and viability were evaluated with Propidium iodide and Hoechst 33258 dyes. Embryos vitrified with sucrose (19.2 percent) and trehalose (26.7 percent ) showed the highest percentage of viable cells and morphological quality.